A bid to block players with English clubs from Scotland duty have been described as “unhelpful and inappropriate” by Scottish Rugby.
Premiership clubs voted not to release Scots for the forthcoming autumn Tests.
“We usually have a good working relationship with PRL and so this tactic by them was both surprising and unnecessary,” said Scottish Rugby.
“We have repeatedly offered to have an independent medical panel review the specifics, but this has not been followed up by PRL (Premiership Rugby Ltd) and its clubs.
“As a union, we take our responsibilities for player welfare seriously and have respected the necessary processes throughout.”
Scottish Rugby revealed that the dispute was the result of an “unresolved medical assessment of the injury status of a player no longer involved in the Scotland squad” from 2013.
“Scottish Rugby has not withheld fees or insurance payments and the costs under dispute are in the tens of thousands,” said the union.
“If an independent arbitration rules that a payment is due then Scottish Rugby will honour that ruling.”
Saracens duo Duncan Taylor and Sean Maitland, Harlequins’ Tim Visser, Exeter’s Moray Low and Scotland captain Greig Laidlaw, of Gloucester, were all selected for Vern Cotter’s latest Scotland squad to face Australia, Argentina and Georgia in November.
However, their participation, along with players from Italy, Samoa and Tonga, had been in doubt over Premiership Rugby’s demand for £400,000 in “unpaid medical costs” from four unions.
The other three unions have now resolved their own disputes with the English clubs.
Scottish Rugby said it “is disappointed in the stance taken by PRL to use a single historic player case as negotiation around player release”.
“The outstanding medical case cited by PRL – relating to one player dating from 2013 – has no connection to any Scottish international currently playing in the Aviva Premiership, so the decision by PRL to threaten the release of current England-based players in this context was both unhelpful and inappropriate,” it added.
Neither side has released the name of the player, or the club involved.
Premiership Rugby did not wish to respond to the latest Scottish Rugby statement.
The league body revealed on Saturday that “the unpaid medical and salary bills caused when a Premiership rugby player was injured on Test duty” would be considered by a World Rugby regulations committee panel in November.